Vertical electrical downtilt antenna

Abstract

A dual-polarization wireless base station antenna that implements vertical electrical downtilt and sidelobe reduction using beam steering circuit that includes a variable power divider and a multi-beam beam forming network. The variable power divider includes a single adjustable control element to divide an input voltage signal into a pair of complimentary amplitude voltage drive signals that exhibit matched phase and constant phase delay through the variable power divider. The beam forming network is configured as a double-sided, edge-connected microstrip module mounted to a main panel, which support the antenna elements in a vertical column organized into sub-arrays in a manner that implements sidelobe reduction. The power distribution network connecting the beam steering network to the antenna elements implements beam tilt bias and sidelobe reduction through coordinated phase shifting implemented through transmission media trace length adjustment.

1. An antenna system comprising:
 an array of antenna elements defining a boresight direction;  
 a variable power divider using a single adjustable control element to divide an input voltage signal into a pair of complimentary amplitude voltage drive signals over a range of voltage amplitude division;  
 a beam forming network receiving the voltage drive signals and producing a plurality of beam driving signals wherein each beam driving signal comprises a component from each voltage drive signal;  
 a power distribution network delivering each beam driving signal to one or more associated antenna elements; and  
 the beam driving signals driving the antenna elements to emit a beam exhibiting a directional tilt with respect to the boresight direction that varies within a range of tilt in response to changes of the voltage amplitude division within the range of voltage amplitude division; and  
 a field adjustable tilt direction actuator for adjusting the voltage amplitude division and thereby adjusting the directional tilt of the beam.  
 
   
   
     2. The antenna system of  claim 1 , further comprising a remote controller for controlling the field adjustable tilt direction actuator. 
   
   
     3. The antenna system of  claim 1 , wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the antenna elements to cause a desired tilt bias of the range of tilt. 
   
   
     4. The antenna system of  claim 3 , further comprising a field adjustable tilt bias actuator for adjusting the tilt bias. 
   
   
     5. The antenna system of  claim 4 , further comprising a remote controller for controlling the field adjustable tilt bias actuator. 
   
   
     6. The antenna system of  claim 1 , wherein:
 the antenna elements are organized into one or more inner sub-arrays located between outer sub-arrays; and  
 each beam driving signal drives an associated antenna sub-array.  
 
   
   
     7. The antenna system of  claim 6 , wherein the number of antenna elements in the outer sub-arrays is greater than the number of antenna elements in the inner sub-arrays for the purpose of reducing sidelobe emission. 
   
   
     8. The antenna system of  claim 7 , wherein:
 the number of outer sub-arrays is two;  
 the number of inner sub-arrays is two;  
 the number of antenna elements in each outer sub-array is four; and  
 the number of antenna elements in each inner sub-array is two.  
 
   
   
     9. The antenna system of  claim 7 , wherein:
 the number of outer sub-arrays is two;  
 the number of inner sub-arrays is two;  
 the number of antenna elements in each outer sub-array is five; and  
 the number of antenna elements in each inner sub-array is three.  
 
   
   
     10. The antenna system of  claim 6 , wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the elements of one or more sub-arrays to cause a desired blurring of the phase matching of the signals emitted by antenna elements of the outer sub-arrays for the purpose of reducing sidelobe emission. 
   
   
     11. The antenna system of  claim 10 , wherein:
 the number of outer sub-arrays is two;  
 the number of inner sub-arrays is two;  
 the number of antenna elements in each outer sub-array is four; and  
 the number of antenna elements in each inner sub-array is four.  
 
   
   
     12. The antenna system of  claim 10 , wherein:
 the number of outer sub-arrays is two;  
 the number of inner sub-arrays is two;  
 the number of antenna elements in each outer sub-array is three; and  
 the number of antenna elements in each inner sub-array is three.  
 
   
   
     13. The antenna system of  claim 6 , comprising two outer sub-arrays and two inner sub-arrays, wherein the beam forming network is a two-by-four orthogonal beam forming network. 
   
   
     14. The antenna system of  claim 6 , comprising two outer sub-arrays and two inner sub-arrays, wherein the beam forming network is a four-by-four Butler matrix. 
   
   
     15. The antenna system of  claim 6 , wherein:
 each antenna element is a dual-polarization antenna element, further comprising a similar a variable power divider, beam forming network, and power distribution network for each polarization; and  
 wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the sub-arrays to cause a desired tilt bias of the range of tilt for each polarization.  
 
   
   
     16. The antenna system of  claim 15 , further comprising a field adjustable tilt bias actuator for adjusting the tilt bias for both polarities in a coordinated manner. 
   
   
     17. The antenna system of  claim 1 , wherein each antenna element is a dual-polarization antenna element, further comprising a similar a variable power divider, beam forming network, and power distribution network for each polarization. 
   
   
     18. The antenna system of  claim 17 , wherein the field adjustable tilt direction actuators are mechanically linked to each other to adjust the beam tilt for both polarities in a coordinated manner. 
   
   
     19. The antenna system of  claim 1 , further comprising:
 a substantially flat main panel defining a longitudinal axis substantially perpendicular to the boresight direction;  
 the main panel supports the variable power divider, the power distribution network, and the array of antenna elements in a spacing configuration having a substantially vertical distribution;  
 the array divided into one or more inner sub-arrays located vertically between outer sub-arrays; and  
 wherein the beam forming network is configured as a double-sided, edge-connected module mounted to the main panel.  
 
   
   
     20. An antenna system comprising:
 an array of antenna elements defining a boresight direction;  
 a variable power divider receiving and dividing an input voltage signal into a pair of matched phase, complimentary amplitude voltage drive signals exhibiting constant phase delay through the variable power divider over a range of voltage amplitude division;  
 a beam forming network receiving the voltage drive signals and producing a plurality of beam driving signals wherein each beam driving signal comprises a component from each voltage drive signal;  
 a power distribution network delivering each beam driving signal to an associated sub-array; and  
 the beam driving signals driving the antenna elements to emit a beam exhibiting a directional tilt with respect to the boresight direction that varies within a range of tilt in response to changes of the voltage amplitude division within the range of voltage amplitude division.  
 
   
   
     21. The antenna system of  claim 20 , further comprising:
 a substantially flat main panel defining a longitudinal axis substantially perpendicular to the boresight direction;  
 the main panel supports the variable power divider, the power distribution network, and the array of antenna elements in a spacing configuration having a substantially vertical distribution;  
 the array divided into one or more inner sub-arrays located vertically between outer sub-arrays; and  
 wherein the beam forming network is configured as a double-sided, edge-connected module mounted to the main panel.  
 
   
   
     22. The antenna system of  claim 21 , wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the sub-arrays to cause a desired tilt bias of the range of tilt. 
   
   
     23. The antenna system of  claim 21 , further comprising a field adjustable tilt bias actuator for adjusting the tilt bias. 
   
   
     24. The antenna system of  claim 21 , wherein the number of antenna elements in the outer sub-arrays is greater than the number of antenna elements in the inner sub-arrays for the purpose of reducing sidelobe emission. 
   
   
     25. The antenna system of  claim 21 , wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the elements of one or more sub-arrays to cause a desired blurring of the phase matching of the signals emitted by antenna elements of the outer sub-arrays for the purpose of reducing sidelobe emission. 
   
   
     26. An antenna system comprising:
 an array of antenna elements defining a boresight direction and one or more inner sub-arrays located between outer sub-arrays;  
 a variable power divider producing complimentary amplitude voltage drive signals over a range of voltage amplitude division;  
 a beam forming network receiving the voltage drive signals and producing a plurality of beam driving signals;  
 a power distribution network delivering each beam driving signal to one or more associated antenna elements;  
 the beam driving signals driving the antenna elements to emit a beam exhibiting a directional tilt with respect to the boresight direction that varies within a range of tilt in response to changes of the voltage amplitude division within the range of voltage amplitude division; and  
 wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the sub-arrays to cause a desired tilt bias of the range of tilt.  
 
   
   
     27. The antenna system of  claim 26 , further comprising:
 a substantially flat main panel defining a longitudinal axis substantially perpendicular to the boresight direction;  
 the main panel supports the variable power divider, the power distribution network, and the array of antenna elements in a spacing configuration having a substantially vertical distribution;  
 the array divided into one or more inner sub-arrays located vertically between outer sub-arrays; and  
 wherein the beam forming network is configured as a double-sided, edge-connected module mounted to the main panel.  
 
   
   
     28. An antenna system comprising:
 an array of antenna elements defining a boresight direction and one or more inner sub-arrays located between outer sub-arrays;  
 a variable power divider producing complimentary amplitude voltage drive signals over a range of voltage amplitude division;  
 a beam forming network receiving the voltage drive signals and producing a plurality of beam driving signals;  
 a power distribution network delivering each beam driving signal to one or more associated antenna elements;  
 the beam driving signals driving the antenna elements to emit a beam exhibiting a directional tilt with respect to the boresight direction that varies within a range of tilt in response to changes of the voltage amplitude division within the range of voltage amplitude division;  
 wherein the number of antenna elements in the outer sub-arrays is greater than the number of antenna elements in the inner sub-arrays for the purpose of reducing sidelobe emission.  
 
   
   
     29. The antenna system of  claim 28 , further comprising:
 a substantially flat main panel defining a longitudinal axis substantially perpendicular to the boresight direction;  
 the main panel supports the variable power divider, the power distribution network, and the array of antenna elements in a spacing configuration having a substantially vertical distribution;  
 the array divided into one or more inner sub-arrays located vertically between outer sub-arrays; and  
 wherein the beam forming network is configured as a double-sided, edge-connected module mounted to the main panel.  
 
   
   
     30. A an antenna system comprising:
 an array of antenna elements defining a boresight direction and one or more inner sub-arrays located between outer sub-arrays;  
 a variable power divider producing complimentary amplitude voltage drive signals over a range of voltage amplitude division;  
 a beam forming network receiving the voltage drive signals and producing a plurality of beam driving signals;  
 a power distribution network delivering each beam driving signal to one or more associated antenna elements; and  
 the beam driving signals driving the antenna elements to emit a beam exhibiting a directional tilt with respect to the boresight direction that varies within a range of tilt in response to changes of the voltage amplitude division within the range of voltage amplitude division; and  
 a field adjustable tilt direction actuator for the adjusting voltage amplitude division and thereby adjusting the directional tilt of the beam; and  
 wherein the power distribution network implements coordinated phase shifting of the beam driving signals delivered to the elements of one or more sub-arrays to cause a desired blurring of the phase matching of the signals emitted by antenna elements of the outer sub-arrays for the purpose of reducing sidelobe emission.  
 
   
   
     31. The antenna system of  claim 30 , further comprising:
 a substantially flat main panel defining a longitudinal axis substantially perpendicular to the boresight direction;  
 the main panel supports the variable power divider, the power distribution network, and the array of antenna elements in a spacing configuration having a substantially vertical distribution;  
 the array divided into one or more inner sub-arrays located vertically between outer sub-arrays; and  
 wherein the beam forming network is configured as a double-sided, edge-connected module mounted to the main panel.